Experimental investigation of motions and global hull girder bending moment of a semi-displacement vessel

• Published in: Ocean engineering 2025-03, Vol.320, p.120295, Article 120295
• Main Authors: Judge, Carolyn Q., Ibrahim, Ahmed M.
• Format: Article
• Language: English
• Subjects: Hull girder loads; Hydrodynamics of high-speed vessels; Nonlinear wave induced bending moment; Semi-displacement vessels; Slamming
• ISSN: 0029-8018
• DOI: 10.1016/j.oceaneng.2025.120295

Slamming load effects are critical for high-speed vessels and they should be considered during design. Modifying the vessel’s primary hull structure to account for underpredicted slamming loads on the hull girder is very costly after the vessel is built; as such, the effect of slamming and whipping loads on longitudinal hull girder strength should be considered during the design cycle. The focus of this paper is to present parametric measurements of a hydro-elastic model test experiment for a semi-displacement vessel traveling in regular waves at Froude numbers of 0.20 to 0.75. The measured data includes heave and pitch motions, wave induced bending moments, and slamming factors. Slamming factor is defined as the ratio of the total hull girder vertical bending moment (VBM) to the wave induced VBM. Slamming factors can be used as a practical approach to incorporate slamming effects on global hull girder loads in finite element analysis. The effects of speed regime (displacement, semi-displacement, and semi-planing), encounter frequency, and steepness on vessel motions, wave induced VBM, and slamming factors are investigated. In general, wave induced VBM were found to be linearly proportional to wave amplitude with minimum effects from wave steepness or vessel speed. In contrast, slamming factors were found to increase with increasing wave steepness and vessel speed, showing higher intensity in the vicinity of the heave natural frequency. In the displacement regime the maximum slamming factor recorded was 2.0, while in the semi-displacement speed regime, the slamming factor increased to 2.6. In the semi-planing speed regime, the maximum slamming factor recorded was 3.7. •Speed, waves, and motions effects on moment and slamming factors are investigated.•Moments and slamming factors increased with increasing wave steepness and speed.•Slams depend on wave steepness and encounter frequency for semi-displacement speed.